That's DRM (Digital Rights Management) right?

Yeah, that has been a problem for some websites lately. Mainly the GGG clips from their site have DRM. That is a big pain in the butt. A lot of the porn sites like COHF flirted with the idea of it, but once they were losing suscribers to their site, they went back to the option of having mpeg clips along with the WMV clips. (I think GGG is one of the few sites that have it still. WCP - West Coast Productions has some DRM clips on their sites too.)

I have no suggestions on how to beat it or work around it. It's really crappy, and especially if you are a paid member of a site, you should be able to download the content you want, store it on a harddrive without any license, or time restraint.
Some people are trying to beat it (you might have to google "DRM", and see if they are any forums that can help you out on the subject.

Personally, I don't think that is the future of porn (I hope not........) but who knows??

Hope this helps.